The objective of this proposal is to investigate the molecular mechanisms by which heavy metals damage nervous tissue. The specific aim of this project is to study the effect of methyl mercury on the nervous tissue, using mouse neuroblastoma and rat glioma cells in culture as experimental models. We propose to perform the following studies: (a) to establish the dose-response relationships for methyl mercury effects upon growth rate and differentiation; (b) to establish the dose-response relationships for methyl mercury effects upon neurotransmitter metabolism; and (c) to establish dose-response relationships for methyl mercury effects upon cyclic nucleotide metabolism. Data may be useful in estimating the relative sensitivity of dividing nerve and glial cells to methyl mercury using the above criteria. Results obtained from this study will show to what extent mercury-induced damage to these cellular functions can be reversed and at what stage these damages become irreversible. The data may also be useful in estimating the maximum permissible concentrations of mercury for the nervous tissue especially in the fetus.